One of Biggest Icebergs Ever Recorded Expected to Break Off from Antarctica

A close-up of the rift on the Larsen C ice shelf. Photo: Swansea University

A giant iceberg the size of Delaware is expected to break away from the Antarctic peninsula, so big it’s likely to be one of the biggest iceberg calving events ever recorded, scientists said Friday.

Researchers at the Swansea University’s College of Science in Wales have been watching the the rift in the Larsen C ice shelf for several years now. The researchers said today the long-running grew suddenly in December and there’s now just 20km of ice keeping the 5,000 sq km piece of ice from floating away.

The Larsen C is approximately 350m thick and floats on the seas at the edge of West Antarctica, holding back the flow of glaciers that feed into it. The loss of a piece this size will leave the whole shelf vulnerable to future break-up, the researchers said.

“If it doesn’t go in the next few months, I’ll be amazed,” said Project leader, Professor Adrian Luckman.

“There hasn’t been enough cloud-free Landsat images but we’ve managed to combine a pair of Esa Sentinel-1 radar images to notice this extension, and it’s so close to calving that I think it’s inevitable.”

According to Professor Luckman, the area that will break off will be about 5,000 sq km in size, which would put the iceberg among the top ten biggest ever recorded.

The researchers have been tracking the rift in Larsen C for several years now following the collapse of the Larsen A ice shelf in 1995 and the sudden break-up of the Larsen B shelf in 2002. They are now concerned about how any break-off will impact the rest of the ice shelf since its neighbor, Larsen B, disintegrated “spectacularly” in 2002 following a similar large calving event.

“We are convinced, although others are not, that the remaining ice shelf will be less stable than the present one,” said Professor Luckman.

“We would expect in the ensuing months to years further calving events, and maybe an eventual collapse – but it’s a very hard thing to predict, and our models say it will be less stable; not that it will immediately collapse or anything like that.”

Professor Luckman added that this is a geographical and not a climate event. Although it is believed that climate warming has brought forward the likely separation of the iceberg, the researchers say they have no direct evidence to support this.

While the iceberg itself is not going to have any impact on sea level rise, a collapse of the entire shelf could raise global sea levels by as much as 10 cm, the researchers said.

“The eventual consequences might be the ice shelf collapsing in years to decades,” said Professor Luckman. “Even the sea level contribution of this area is not on anybody’s radar; it’s just a big geographical event that will change the landscape there.”

Giant icebergs such as this one usually present little threat to shipping, since they break up and melt before floating into busy shipping lanes or sometimes simply float around Antarctica.